Eagles Be Gone

We turned to experts for help with our golden eagle problem. We knew we had to capture and relocate golden eagles from the islands, in order to reduce, if not eliminate, predation pressure on island foxes. Gary had estimated that, given what golden eagles eat, maybe half a dozen golden eagles were on the islands and preying upon foxes. We brought in Brian Latta from the Santa Cruz Predatory Bird Research Group, and he led a capture effort that utilized a number of methods to attract and trap golden eagles. He primarily used a bownet trap, for which he baited eagles in with a dead pig. When the eagle alighted on the prey, Brian, from a mile away (golden eagles are very wary), would trigger a net to close over the eagle, powered by a garage door spring. This method brought in a dozen golden eagles in the first year, twice as many as we had estimated to be on the islands. Captured eagles were boated off the islands and released in the very northeastern corner of California (no other states wanted them). Brian affixed satellite transmitters to those first dozen eagles, and none came back to the Channel Islands, underscoring the fact that the islands were, in fact, pretty marginal habitat for golden eagles. Goldens specialize on rabbits and ground squirrels, of which there are none on the islands, and so when released in the eastern Sierra-Cascades, where there were plenty of rabbits and ground squirrels, eagles saw no reason to return to a hard-scrabble existence on the islands. The prey remains in island golden eagle nests told us this, as well. On the islands, golden eagles were hunting mice and even nocturnal skunks, evidence of a certain amount of desperation. No self-respecting eagle would ever take a skunk.

Trouble was, as Brian said, in any animal removal program, you get the dumb ones first. The eagles that remained were less inclined to be captured by bownets, and so Brian turned to other methods. He put a net in an eagle territory and tethered a great horned owl nearby (golden eagles HATE that). Eagles were not fooled by the net, however. We tried capturing them from a helicopter, but the first helicopter we used was actually outflown and outmaneuvered by the golden eagles we attempted to capture. They are impressive birds, and formidable opponents. Nestling golden eagles were plucked from the nests by biologists who scrambled into them, and the last breeding eagle pair was removed in 2006 by capturing them at the nest. All in all, 44 golden eagles, including a dozen eaglets from nests, were captured and released on the mainland. Golden eagles successfully colonized the islands in the mid-1990s, and had actually begun sending colonizers back to the mainland.

Golden eagle removal was, in the end, successful, as none returned to the islands. But it took longer than we had realized it would, and there were still some golden eagles on the islands when we started releasing foxes back to the wild in 2003-2004.